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Howlett" , Mark Rutland , Masami Hiramatsu , Matt Turner , Max Filippov , Michael Ellerman , Michal Simek , Oleg Nesterov , Palmer Dabbelt , Peter Zijlstra , Richard Weinberger , Russell King , Song Liu , Stafford Horne , Suren Baghdasaryan , Thomas Bogendoerfer , Thomas Gleixner , Uladzislau Rezki , Vineet Gupta , Will Deacon , bpf@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-trace-kernel@vger.kernel.org, linux-um@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev, sparclinux@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v6 6/8] x86/module: prepare module loading for ROX allocations of text Message-ID: References: <20241016122424.1655560-1-rppt@kernel.org> <20241016122424.1655560-7-rppt@kernel.org> <20241016170128.7afeb8b0@gandalf.local.home> <20241017101712.5a052712@gandalf.local.home> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Post: List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241017101712.5a052712@gandalf.local.home> On Thu, Oct 17, 2024 at 10:17:12AM -0400, Steven Rostedt wrote: > On Wed, 16 Oct 2024 17:01:28 -0400 > Steven Rostedt wrote: > > > If this is only needed for module load, can we at least still use the > > text_poke_early() at boot up? > > > > if (ftrace_poke_late) { > > text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL); > > } else if (system_state == SYSTEM_BOOTING) { > > text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE); > > } else { > > mutex_lock(&text_mutex); > > text_poke((void *)ip, new_code, MCOUNT_INSN_SIZE); > > mutex_unlock(&text_mutex); > > } > > > > ? > > > > The above if statement looks to slow things down just slightly, but only by > > 2ms, which is more reasonable. > > I changed the above to this (yes it's a little hacky) and got my 2ms back! > > -- Steve > > DEFINE_STATIC_KEY_TRUE(ftrace_modify_boot); > > static int __init ftrace_boot_init_done(void) > { > static_branch_disable(&ftrace_modify_boot); > return 0; > } > /* Ftrace updates happen before core init */ > core_initcall(ftrace_boot_init_done); We can also pass mod to ftrace_modify_code_direct() and use that to distinguish early boot and ftrace_module_init. With this I get very similar numbers like with the static branch diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 8da0e66ca22d..859902dd06fc 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -111,17 +111,22 @@ static int ftrace_verify_code(unsigned long ip, const char *old_code) */ static int __ref ftrace_modify_code_direct(unsigned long ip, const char *old_code, - const char *new_code) + const char *new_code, struct module *mod) { int ret = ftrace_verify_code(ip, old_code); if (ret) return ret; /* replace the text with the new text */ - if (ftrace_poke_late) + if (ftrace_poke_late) { text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL); - else + } else if (!mod) { text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE); + } else { + mutex_lock(&text_mutex); + text_poke((void *)ip, new_code, MCOUNT_INSN_SIZE); + mutex_unlock(&text_mutex); + } return 0; } @@ -142,7 +147,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long ad * just modify the code directly. */ if (addr == MCOUNT_ADDR) - return ftrace_modify_code_direct(ip, old, new); + return ftrace_modify_code_direct(ip, old, new, mod); /* * x86 overrides ftrace_replace_code -- this function will never be used @@ -161,7 +166,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) new = ftrace_call_replace(ip, addr); /* Should only be called when module is loaded */ - return ftrace_modify_code_direct(rec->ip, old, new); + return ftrace_modify_code_direct(rec->ip, old, new, NULL); } /* -- Sincerely yours, Mike.